It has long been known in the art that methylchlorosilanes can be prepared by the direct reaction of particulate silicon and methyl chloride in the presence of metallic copper or silver catalyst. These reactions are disclosed in the literature, e.g. Rochow, U.S. Pat. No. 2,380,995 and Rochow, U.S. Pat. No. 2,383,818. In addition to dimethyldichlorosilane, a variety of other silanes can be formed such as tetramethylsilane, trimethylchlorosilane, methyltrichlorosilane, silicon tetrachloride, trichlorosilane, methyldichlorosilane and dimethylchlorosilane.
In addition to dimethyldichlorosilane, which is generally viewed as the most commercially attractive methylchlorosilane, a residue is produced during the formation of the methylchlorosilane crude. The residue is comprised of products in the methylchlorosilane crude having a boiling point above about 70.degree. C. at atmospheric pressure. The residue contains such materials as disilanes, for example, symmetrical 1,1,2,2-tetrachlorodimethyldisilane, 1,1,2-trichlorotrimethyldisilane, disiloxanes, silylmethylenes and other higher boiling species, for example, trisilanes, trisiloxanes, trisilylmethylene, etc.
It is further known in the art that certain components in the residue, mostly the highly chlorinated disilanes such as 1,1,2,2-tetrachlorodimethyldisilane and 1,1,2-trichlorotrimethyldisilane, can be "cleaved" in accordance with the teachings of Bluestein, U.S. Pat. No. 2,709,176, to produce useful methylchlorosilane monomers. Cleavage of the highly chlorinated disilanes can be effected by anhydrous hydrogen chloride in the presence of a tertiary amine catalyst to form monomers. The monomers are then distilled overhead and the remaining distillate, also known as the residue of the residue, is comprised of unreacted disilanes, disiloxanes and silylmethylenes. Prior to the present invention this residue of the residue was typically considered to have little or no commercial value.
It has now been found that a substantial portion of the residue of the residue stream can be converted into a useful product by hydrolyzing the components of this stream to form a silicone fluid comprising a novel siloxane polymer. Surprisingly, these silicone fluids have now been found to be a suitable replacement for linear and branched linear methyl siloxane polymers or fluids, such as emulsions and antifoam compounds.
Further, it has now been found that the residue of the residue stream provides a source for fully alkylated linear and cyclic siloxanes with disilane, disiloxane and/or silylmethylenes bonds.